1. Field of the Invention
The present invention relates generally to a wireless telecommunication system, and in particular, to a method of determining whether a wireless packet data service can be activated in a dormant state with no traffic channel connected between a base station (BS) and a mobile station (MS).
2. Description of the Related Art
Wireless telecommunication systems such as code division multiple access (CDMA) 2000 provide 3rd generation mobile communication. These 3rd generation mobile communication systems support high-speed packet data service including moving pictures as well as voice service, as compared to traditional 2nd generation mobile communication systems.
If traffic is not exchanged between a BS and an MS for a predetermined time after radio channels are connected for a packet data service, they exchange signaling messages and then enter a dormant state. The dormant state refers to a state where no traffic channels are connected between the BS and the MS, all channels in Layer 1 and Layer 2 are released, and information about the Layer 1 and 2 channels is deleted. Yet, the MS maintains a service instance for the packet data service in the dormant state. A service instance is defined as a process for enabling the packet data service to proceed and managing related connection information, specifically point-to-point protocol (PPP) connection information. The service instance is identified by a service reference identifier (SR ID).
In the dormant state, only the PPP connection information is managed. Upon generation of transmission data in the dormant state, the BS and the MS enter a reconnection state and perform the same operation as done for an initial call setup, excluding setup of the PPP connection. If the packet data service can be activated in the reconnection state, the BS and the MS transition to an active state and exchange packets.
To activate a particular service in the dormant state, the BS notifies the MS of only a service option indicating the type of the service. It may occur that two or more services having the same service option are in progress between the BS and the MS. For example, with the MS connected to a laptop computer, the MS and the laptop computer perform a video on demand (VOD) service and a file transfer protocol (FTP) service, respectively, by the same wireless connection. In this case, the MS runs two service instances for the VOD and FTP. Although the service instances have the same service option number, for example, 33, indicating the high-speed packet data service, they use separate PPP connections.
After establishing traffic channels and transitioning to the active state, the MS identifies the service to be activated by an SR ID received from the BS, and determines whether a corresponding service instance is available. If the MS is disconnected from the laptop computer in the dormant state, the FTP service is unavailable. When the BS requests activation of the FTP service by the SR ID identifying the FTP service, the MS releases the assigned traffic channels, considering the FTP service instance is unavailable.
Because the BS does not notify the MS of the SR ID indicating the service to be activated before the traffic channel assignment, the traffic channels are assigned and messages are exchanged for a service connection between them even if the MS cannot resume the service instance for the service. Thus, unnecessary signaling messages and traffic continue to be generated until the service is terminated and the MS and the BS occupy the assigned traffic channels until they confirm the unavailability of the service activation. As a result, radio resources are wasted and unnecessary time delay is produced until the termination of the service.